Optical characterization of proton irradiated diamond

ABSTRACT Manufacturing of miniaturized photonic devices based on diamond technology is possible by implanting the pristine material with highly energetic particles. Here we report on the spectral characterization of the optical constants of proton-irradiated diamond. Absorption of the irradiated zones was estimated in the UV-vis-NIR from direct transmittance measurement using a dedicated setup with enhanced spatial resolution. The OPD data providing an estimation of the thickness of the damaged area and its depth profile, have allowed then evaluation of the extinction coefficient from the transmission measurements. Simultaneous variation of dispersive optical constants makes the modeling significantly more complicated compared to the above cited monochromatic study. Keywords: Optical constants; Diamond crystal; Ion implantation 1. INTRODUCTION Manufacturing of miniaturized photonic devices based on diamond technology is possible by implanting the pristine material with highly energetic particles. Theoretically the optical constants of irradiated material may vary from the values typical for pristine diamond to those of graphite, however only precise knowledge of the optical constants allows calculation of performance of the novel photonic micro- and nano-devices like e.g. diamond-based waveguiding structure

Spectroscopic measurement of the refractive index of ion-implanted diamond

We present the results of variable-angle spectroscopic ellipsometry and transmittance measurements to determine the variation of the complex refractive index of ion implanted single-crystal diamond. An increase is found in both real and imaginary parts at increasing damage densities. The index depth variation is determined in the whole wavelength range between 250 and 1690 nm. The dependence from the vacancy density is evaluated, highlighting a deviation from linearity in the high-damage-density regime. A considerable increase (up to 5%) in the real part of the index is observed, attributed to an increase in polarizability, thus offering new microfabrication possibilities for waveguides and other photonic structures in diamond.Comment: 3 pages, 4 figure

Pulsed laser treatment of gold and black gold thin films fabricated by thermal evaporation

AbstractThe effect of pulsed laser treatment of metal, and metal blacks, was studied. Gold and black gold thin films were fabricated by thermal evaporation of gold in a vacuum and nitrogen atmosphere respectively. Black gold films were grown in a nitrogen atmosphere at pressures of 200 Pa and 300 Pa. UV pulsed laser radiation (λ = 266 nm, τ = 4 ns), with fluence ranging from 1 mJ·cm−2 to 250 mJ·cm−2 was used for the film treatment in a vacuum and nitrogen atmosphere. The nitrogen pressure was varied up to 100 kPa. Surface structure modifications were analyzed by optical microscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy (EDX) was used for chemical characterization of the samples. A significant dependence of the film optical and structural properties on laser treatment conditions (laser fluence, ambient pressure and number of applied pulses) was found. The threshold for observable damage and initiation of changes of morphology for gold and black gold surfaces was determined. Distinct modifications were observed for fluences greater than 106 mJ·cm−2 and 3.5 mJ·cm−2 for the gold and black gold films respectively. Absorbtivity of the black gold film is found to decrease with an increase in the number of laser pulses. Microstructural and nanostructural modifications after laser treatment of the black gold film were observed. EDX analysis revealed that no impurities were introduced into the samples during both the deposition and laser treatment

Small dimensions portable instruments for in-situ multispectral imaging

The design of a compact spectrometer for analysis of artworks is presented. Its operation is based on the use of a variable transmission filter associated with an array detector. The instrument allows the measurement of the spectral reflectance factor and combines the acquisition of data in a continuous spectrum with the small dimension that is of primary importance for in-situ spectral imaging. Keywords: compact spectrometers, image spectrometry, optical filter

A portable Spectro-photo/radio-metric Camera with Spatial Filtering for VIS-NIR Imaging

This work proposes the design of a miniaturized spectrophoto/radio-metric camera with spatial filtering of the light for measuring the spectral reflectance factor and the spectral radiance of the objects of a scene

Spatial filtering of visible light in a spectrophotometric camera for artwork imaging

The preservation and reproduction of a still artwork needs the knowledge of its spectral reflectance, obtainable in laboratory by spectrophotometric scanners. This work proposes the design of a miniaturized spectrophotometric camera with spatial filtering of the light for measuring the spectral reflectance factor and the spectral radiance of the objects of a scene

Growth of Magnetron-Sputtered Ultrathin Chromium Films: In Situ Monitoring and Ex Situ Film Properties

We report a systematic nanoscale investigation on the ultrathin Cr film growth process and properties. Polycrystalline metallic films were manufactured by magnetron sputtering on fused silica substrates. The film growth was observed in situ by broad-band optical monitoring (BBM) and plasma-emission spectroscopy (OES) methods. The ex situ characterization of the Cr films with thicknesses varying from 2.6 nm up to 57 nm were performed by both non-destructive and destructive techniques. Recently, we reported on a novel set of data for optical and electrical properties of sputtered chromium films. The optical and electrical properties of the films are known to be governed by their structure and microstructure, which were analyzed in detail in the present research. Moreover, the optical properties of the films were studied here in a significantly wider optical range and obtained using both in situ and ex situ measurements. Reliable in situ nanoscale characterization of metal films was shown to ensure an unfailing approach in obtaining ultrathin layers with desirable thickness and stable and well-determined optical constants and electrical conductivity. This is of high importance for various industries and novel upcoming applications

Optical and photoacoustic investigation of AZO/Ag/AZO transparent conductive coating for solar cells

Great attention has been recently paid to transparent conductive oxides (TCOs) due to their application in optoelectronic devices, flat panel displays, solar cells, and anti-static coatings. Concerning photovoltaic applications, the reduction of the material and processing costs are the key factors in the production process. Due to In scarcity and cost, alternative solutions to indium tin oxide (ITO) are needed. Al-doped ZnO (AZO) meets the requirements for application in thin film solar cells, thanks to its good optoelectrical properties, low cost and higher resistance to Hydrogen-reach plasmas. Recently many papers analyze innovative AZO based TCO structures where a thin layer of Silver is introduced in the TCO so to increase the electrical conductivity without loosing transparency. In this work we study the transparency and the electrical sheet resistance of a multilayer AZO/Ag/AZO as a function of the silver thin layer, and discuss the problem of optimizing the thicknesses of the multilayers to get the best performances. We have realized an AZO/Ag/AZO multilayer coating by radio frequency (RF) sputtering with an optimal thickness of the silver layer. Optical and photoacoustic spectroscopy (PAS) have been applied to perform the characterization of the sample. In particular PAS seems the most efficient technique to test directly the absorbance of the structure which should be reduced to avoid overheating and loss of the solar cell efficiency